Investigation of tribological behavior of poly(methyl methacrylate) biocomposite containing hydroxyapatite

Poly(methyl methacrylate) (PMMA), is widely used in biomedical applications such as bone cement. However, it is known to have low wear resistance. To enhance its tribological behavior, a reinforcement phase is necessary. For this purpose, in this study, homemade hydroxyapatite (HAp) was utilized to enhance the mechanical properties and wear resistance of PMMA while also increasing its biocompatibility. Using the thermal extraction method, natural raw materials were used to synthesize homemade HAp powder successfully. The d _0.5 of HAp powders in particle size analysis was 7.464 μm. Hot isostatic pressing (HIP) was used to create PMMA–HAp biocomposites with various HAp ratios (5, 10 and 15 wt%) in PMMA. The wear morphology was characterized by scanning electron microscopy (SEM). The SEM images showed a severe abrasive wear mechanism, but a relatively stable wear surface was observed that indicated slight abrasion during the wear tests with the increase in HAp ratio. The highest wear rate was obtained in 15% HAp-reinforced PMMA at a sliding speed of 1.0 m/s and had value of 4.72 × 10⁻⁴ mm³/(N m) under a 20 N load. The HIP’ed densities of the samples increased from 1.15 to 1.31 g/cm³ with increasing amount of HAp. Similarly, the Vickers test results showed that the hardness values increased from 14.76 to 22.03 HV.